/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.runners.core.construction;



import com.google.auto.service.AutoService;

import com.bff.gaia.unified.model.pipeline.v1.RunnerApi;



import java.util.Iterator;

import java.util.ServiceLoader;

import java.util.function.Predicate;



/**

 * An extension point for users to define their own native transforms for usage with specific

 * runners. This extension point enables shared libraries within the Apache Unified codebase to treat

 * the native transform as a primitive transforms that the runner implicitly understands.

 *

 * <p><b>Warning:</b>Usage of native transforms within pipelines will prevent users from migrating

 * between runners as there is no expectation that the transform will be understood by all runners.

 * Note that for some use cases this can be a way to test out a new type of transform on a limited

 * set of runners and promote its adoption as a primitive within the Apache Unified model.

 *

 * <p>Note that users are required to ensure that translation and execution for the native transform

 * is supported by their runner.

 *

 * <p>Automatic registration occurs by creating a {@link ServiceLoader} entry and a concrete

 * implementation of the {@link IsNativeTransform} interface. It is optional but recommended to use

 * one of the many build time tools such as {@link AutoService} to generate the necessary META-INF

 * files automatically.

 */

public class NativeTransforms {

  /**

   * Returns true if an only if the Runner understands this transform and can handle it directly.

   */

  public static boolean isNative(RunnerApi.PTransform pTransform) {

    Iterator<IsNativeTransform> matchers = ServiceLoader.load(IsNativeTransform.class).iterator();

    while (matchers.hasNext()) {

      if (matchers.next().test(pTransform)) {

        return true;

      }

    }

    return false;

  }



  /** A predicate which returns true if and only if the transform is a native transform. */

  public interface IsNativeTransform extends Predicate<RunnerApi.PTransform> {

    @Override

    boolean test(RunnerApi.PTransform pTransform);

  }

}